1. Field of the Invention
This invention relates generally to textile fabrication apparatus, and more specifically to an apparatus for aligning and depositing weft textile yarns, threads or filaments onto aligned warp textile yarns or filaments while controlling and unifying the tension in the weft yarns to produce non-woven fabrics having the appearance of woven fabrics.
2. Description of Background Art
Traditionally, fabrics having generally perpendicularly extending warp and weft yarns have been woven with a loom so that the yarns extending in one direction pass over and under the yarns extending in the perpendicular direction. The yarn densities in both the warp and weft directions, however, are limited not only by the diameters of the yarns extending in the respective warp or weft directions but by the sizes of the orthogonally-extending yarns over and under which they are woven. Because woven yarns are typically comprised of yarns that extend in parallel and orthogonal directions in regular patterns, these fabrics are generally aesthetically pleasing especially when compared to traditional non-woven fabrics. The weaving of woven fabrics, however, is a relatively time consuming process having maximum production rates of around 10 ft/minute or less making woven fabrics expensive when compared to nonwoven fabrics.
Traditional nonwoven fabrics comprise non-aligned, generally randomly orientated yarns that are bound into a fabric mat. These types of fabrics can be produced at extremely high rates of speed up to an order of magnitude greater than woven fabrics. Further, depending on the adhesives used to join the yarns together, traditional non-woven fabrics can have physical properties equal to or in excess of woven fabrics of comparable thicknesses and densities. In variations of the traditional non woven mat fabrics a certain portion of the yarns may be aligned in one or more directions to create fabrics with anisotropic properties. Traditional nonwoven fabrics are generally not particularly aesthetically pleasing and as such are not used very often in applications where appearance is important.
Nonwoven fabrics that comprise a layer of aligned weft yarns and a layer of aligned warp yarns are also known that resemble woven fabrics. The warp and weft yarns of either layer do not intermingle, rather, an aligned planer layer of warp yarns overlies an aligned layer of weft yarns, wherein the two layers are typically joined together by a mechanical, thermal or chemical means, such as adhesive bonding. Because the layers do not intermingle, each yarn is uncrimped as it passes over or under other yarns. The result is a fabric with superior physical characteristic when compared to woven fabrics depending on the manner in which the warp and weft layers are joined together. Further, because the yarns do not pass over and under one another, very high potential fiber densities are potentially possible in both the weft and warp directions. Another advantage of nonwoven fabrics is that they have the potential to be produced faster and cheaper than comparable woven fabrics.
As known in the prior art, a nonwoven fabric having the appearance of a woven fabric can be formed by pulling a sheet of aligned warp yarns over a cylindrical form as weft yarns are wound around the warp yarns. Typically, there is an adhesive on the warp fibers that bind the two layers together. The resulting tubular cloth is then cut in the warp direction and wound onto a take-up roll. For a variety of reasons, however, the prior art machines have not been able to deliver in producing low cost woven-appearing nonwoven fabrics that also have high density yarn counts.
Several of the prior art apparatus for producing woven-appearing nonwoven fabrics were designed to produce fabrics comprised of reinforcing fibers such as fiberglass and were not intended to produce high density woven fabric replacements. U.S. Pat. No. 2,797,728 of Slayer et. al. and U.S. Pat. No. 4,265,691 of Usui each describe an apparatus for making a fiberglass nonwoven fabric for use as a reinforcement for subsequently produced composite materials. The described apparatus are not configured or designed to permit the rapid production of fabrics with tightly compacted warp and weft layers.
PCT publication WO 80/02850 describes an apparatus for producing nonwoven fabric, however, the manner in which the weft yarns are deposited upon the warp yarns is not amenable to the rapid production of fabrics having a dense weft layer. It can be appreciated that even small lateral movement of a weft yarn as it is deposited onto the warp yarns will cause the weft yarn to overlap an adjacent weft yarn, a configuration that is generally unacceptable in a finished high density nonwoven fabric that is intended to resemble and substitute for a dense traditionally woven fabric.
It is to overcome the shortcoming in prior art apparatus that the apparatus of the present invention has been developed.